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PURPOSE: Although visual impairment is a well-recognized consequence of cataract development, little is known about the ability of the melanopsin-based photosensitive retinal ganglion cells (pRGCs) to regulate sleep-wake timing in the presence of cataract. In this study, we replaced a cataractous natural crystalline lens with two different types of artificial intraocular lenses, a UV-blocking lens or a blue-filtering lens. We investigated the level of sleep disturbance before cataract surgery and any change in sleep due to improved light transmission following surgery and compared this in both types of intraocular lens. METHODS: Quality of sleep in 961 patients undergoing cataract surgery was assessed by administering the validated self-reported Pittsburgh Sleep Quality Index (PSQI) questionnaire. The PSQI distinguishes good sleepers from poor sleepers by scoring seven different sleep components over the last month, which are combined to produce an overall score for sleep quality. Patients received either an ultraviolet-blocking (UVB) clear intraocular lens (IOL) or a blue-filtering (BF) IOL. Questionnaires were completed four times: 1 month preoperatively and again 1, 6 (UVB-IOL only), and 12 months postoperatively. RESULTS: Half of the patients reported poor sleep in the presence of cataract in both the UVB-IOL (mean PSQI = 6.35; SD = 3.82) and BF-IOL (mean PSQI = 6.39; SD = 4.04) groups. Cataract removal improved overall sleep quality significantly 1 month postoperatively in the UVB-IOL (mean PSQI = 5.89; SD = 3.71) and BF-IOL (mean PSQI = 6.08; SD = 3.88) groups. Sleep latency also improved for the UVB-IOL (preoperative mean = 1.16; SD = 1.003) and BF-IOL (preoperative mean = 1.17; SD = 1.03) groups at 1 month (UVB-IOL group mean = 1.01; SD = 0.923 and BF-IOL group mean = 1.00; SD = 0.95), which was sustained at 6 months for the UVB-IOL group (mean = 1.02; SD = 0.93) and 12 months for both the UVB-IOL and BF-IOL groups (6 months: UVB-IOL group mean = 0.96; SD = 0.92 and for the BF-IOL group mean = 0.99; SD = 0.96). CONCLUSIONS: Overall sleep quality and sleep latency improves after removal of cataract irrespective of the type of IOL implanted. These data show that implantation of BF-IOL does not have a negative impact on the sleep-wake cycle.